Can lichen planus cause a single persistent nonhealing tongue sore for over a year?

No: The rule of thumb is that any oral lesson that lasts more than 2 weeks MUST be evaluated. Please see your General Dentist or Physician, or Specialist Oral Surgeon or ENT, immediately. What not to do: Put this off. Be sure to report if you some anything, chew tobacco, or abuse alcohol. Bring a list of all your Meds/OTC's/Supplements with you.